Best time to fly Miami to Portland

Every month pooled across the years on record, so "July" means July generally rather than one particular July. Full MIA to PDX record →

Best month

April

83.3% on time · 102 flights

Worst month

August

40% on time · 5 flights

Month Flights On time Cancelled When late, by
January 121 73.5% 2.48% 56 min
February 108 69.5% 1.85% 95 min
March 122 65% 1.64% 86 min
April 102 83.3% 0% 71 min
May 43 69.8% 0% 84 min
June 2 50% 0% 244 min
July 31 70% 3.23% 124 min
August 5 40% 0% 80 min
November 70 71% 0% 61 min
December 120 60.2% 0% 60 min

What a seasonal pattern can and cannot tell you

Months differ for reasons that repeat — summer thunderstorms in the American interior, winter fog and de-icing in northern Europe, school holidays filling every seat and leaving no slack in the schedule. Those are real and they come back each year.

What the pattern cannot do is forecast a particular flight. A quiet month has late days and a bad month has punctual ones. Treat this as a way to choose between two dates you are indifferent about, not as a promise.